US Secretary of State John Kerry holds a news conference at the State Department headquarters at the Harry S. Truman building January 5, 2017 in Washington, DC. (Photo by AFP)n

US Secretary of State John Kerry has hailed the outgoing Obama administration for its efforts to sign the landmark nuclear agreement with Iran.

In his departure memo issued on Thursday, Kerry said the 2015 deal cut off all pathways for Iran to develop what he called a nuclear weapon.

“After reaching out to Iran through bilateral channels and more than two and a half years of intense multilateral negotiations, the United States, the United Kingdom, France, Germany, Russia, China, the European Union and Iran agreed on the Joint Comprehensive Plan of Action (JCPOA), an agreement that has verifiably cut off all of Iran’s pathways to a nuclear weapon,” he said.

Iranian nuclear negotiators, headed by Foreign Minister Mohammad Javad Zarif, (3rd R) meet the US delegates, headed by Secretary of State John Kerry (3rd L) in the Swiss city of Lusanne, March 17, 2015. (Photo by AFP)

The top US diplomat argued that the nuclear accord was a result of crippling sanctions engineered by the United States against the Islamic Republic.

He then described Iran-US relations as contentious and called for maintaining pressure on the Islamic Republic to undermine its missile program, and went on to accuse Iran of supporting terrorism.

“Our relationship remains highly contentious – and we must maintain our pressure and continue to push back on Iran’s missile program, its support for terrorism, its disregard for human rights, and its destabilizing interference in the affairs of its neighbors as long as these threats persist,” Kerry said.

Iran and the P5+1 group of countries reached the nuclear agreement in July 2015.

In accordance to the JCPOA, which took effect in January, Iran has undertaken to put limitations on its nuclear program in exchange for the removal of nuclear-related sanctions.

US Secretary of State John Kerry talks with Iranian Foreign Minister Mohammad Javad Zarif in Vienna, January 16, 2016. (Photo by AFP)

The Obama administration, however, has continued to maintain sanctions on Iran and a number of Iranian companies and individuals, prompting complaints from Tehran that Washington is failing to implement its side of the deal.

The United States, Israel, and some of their allies have accused Iran of pursuing military objectives in its nuclear energy program.

Washington and its allies had imposed illegal sanctions on Iran based on the unfounded accusation that Tehran is pursuing non-civilian objectives in its nuclear program.

Iran rejects the allegation, arguing that as a committed signatory to the nuclear Non-Proliferation Treaty (NPT) and a member of the International Atomic Energy Agency (IAEA), it has the right to use nuclear technology for peaceful purposes.

In addition, Iran says it is forbidden to use weapons of mass destruction from a religious point of view, as highlighted on many occasions by the country’s spiritual leaders.

But still Kerry argued in his departure memo, “In reaching and implementing this deal, we took a major security threat off the table without firing a single shot. The United States, our partners and allies in the Middle East (including Israel), and the entire international community are safer today because of the JCPOA.”

Donald Trump addresses the American Israel Public Affairs Committee (AIPAC) 2016 Policy Conference at the Verizon Center in Washington, DC, March 21, 2016. (Photo by AFP)

Elsewhere in a news briefing on Thursday, Kerry warned US President-elect Donald Trump about a possible cancellation of the Iran deal.

During his presidential campaign, Trump, who defeated his Democratic rival Hillary Clinton in the November 8 election, had promised to annul the deal.

He called the pact a “disaster” and “the worst deal ever negotiated.” He also said that the deal could lead to a “nuclear holocaust.”